1. Field of the Invention
The present invention is directed to an x-ray detector for acquiring an x-ray image of the type composed of a scintillator which generates an optical image and an arrangement for acquiring the generated optical image.
2. Description of the Prior Art
X-ray detectors of the above general type are utilized for medical purposes in x-ray diagnostics installations.
X-ray detectors currently obtainable in the marketplace usually have a quadratic or rectangular shape. Thus, x-ray films with reinforcing or intensifier film and storage film systems have a rectangular format. The solid-state matrix detectors of cesium iodide (Csl) and amorphous silicon (a-Si) disclosed in European Application 0 189 710 and currently being developed or, as disclosed in U.S. Pat. No. 5,313,066, composed of selenium (Se) and a-Si, also have a rectangular quadratic format.
X-ray image intensifiers, by contrast, have a round structure through which x-rays enter so that a circular x-ray image is produced.
There are types of x-ray exposures wherein it is desirable to come as close as possible to the human body with the x-ray exposure system. In, for example, mammographic exposures, it is desirable to examine the tissue close to the chest wall. In thorax exposures, the neck of the patient should also be imaged. The existing x-ray exposure systems with their formats are not optimally suited for such purposes.
Heretofore, x-ray exposure systems were designed such that the x-ray-sensitive surface extends to the edge of the detector at least at one side. Thus, the spacing from the chest wall of the x-ray film in the film-foil cassette of a mammographic diagnostic installation only amounts to a few millimeters. It is possible to get that close to the chest wall of the patient at only one location.